"What Does ‘Green’ Open Access Mean? Tracking Twelve Years of Changes to Journal Publisher Self-Archiving Policies"
Elizabeth Gadd and Denise Troll Covey have self-archived "What Does 'Green' Open Access Mean? Tracking Twelve Years of Changes to Journal Publisher Self-Archiving Policies."
Here's an excerpt:
Traces the 12-year self-archiving policy journey of the original 107 publishers listed on the SHERPA/RoMEO Publisher Policy Database in 2004, through to 2015. Maps the RoMEO colour codes 'green', 'blue', 'yellow' and 'white') and related restrictions and conditions over time. Finds that while the volume of publishers allowing some form of self-archiving (pre-print, post-print or both) has increased by 12% over the twelve years, the volume of restrictions around how, where, and when self-archiving may take place has increased 119%, 190% and 1000% respectively.